An expeditious route to methyl-7-oxo-1,4,5,8-tetramethylbicyelo[3.3.0]octane-3-carboxylate from a simple aromatic precursor is described. Oxidative dearomatization of 2-hydroxymethyl-3,4,6-trimethylphenol into spiroepoxycycloliexa-2,4-dierone, its cycloaddition and triplet-sensitized 1,2-acyl shift, and stereochemical inversion are the key features Of Our methodology.